Turbo'd/Blown Reliability

[rfabro]

I really want a turbo on my Phazer Mountain lite so I can go anywhere. I really don't want a machine whose reliability is dubious while in the back country and in the deep. The MCXpress turbo I'm looking at boosts 12psi. What do you guys who have or have had forced induction on their sleds think about reliability? It would be worth it to me if I only had to rebuild once a year and if reliability all winter was not an issue.

 

[TurboJamie]

I'd leave the phazer for a season see how the engine holds up then try for next year.

 

[rfabro]

How much boost do you run on your apex? How many miles after turbo?

 

[rideblue]

If you keep the boost levels at resonable level for your elevation, the engine should have no durability problems. The million dollar question is what that number is! There are several Apex and RX sleds running around here at 10 psi on pump gas for thousands of miles with out durability issues.

I have the MCX on my demo mountain lite installed by High Altitude Boost. Did the head shim and all. At the elevation we ride, 10,000 ft and up, the sled runs great once boost is above 7 or 8psi. Runs best at 10psi to 14psi. Below 8psi it has very little low end. Moved air filter out from under seat and installed turbo blanket and exhaust wrap but still has poor low end power. Stocker has much better low end grunt. Going to remove head shim, go back to stock compression and turn boost down to get the low end back and turbo to spool faster.

 

[rfabro]

Thanx for the info, blue. Sounds like if I never boost above 12 psi
I should be ok. How's the snow there? I know your neck of the woods a bit -
lived in Leadville for a bit. High altitude is the best reason for turbo vs.
blower- no loss of power! Let me know how those new mods work out.

 

[rideblue]

The sled worked much better this past weekend. Removing the head shim and installing 2 head gaskets brought the low end power back. Running 8 to 9 psi it runs like a 800 or 900 2 stroker.

Snow around here is not the best right now. Marshall pass is better that cottonwood or hanncock - st. elmo.
Wolf creek and summitville are the best.

 

[teerex]

What's the difference between a head shim and 2 head gaskets ?

 

[rfabro]

Thanx for reply, blue. MCX runs the turbo setup 12psi with head shim. Still poor low end? Dealer who has turbo mtn lite says low end is perfect for boondockin' with no lag. He says blower power too abrupt for tight woods. Sounds like I may like your set up better- should have more endurance as far as pressure side staying sealed. Still running straight pump gas? Also I've heard of intake sucking exhaust. Did you make snorkel to air filter?

 

[rideblue]

Head shim is much thicker than 2 head gaskets, .060 or bigger?, have not measured it yet. Did 2 for a little extrs insurance.
We installed a 180 degree rubber hose on intake to get the filter out from under the seat. Runs way more consistant, boost went up 2psi and turbo spools faster. Going to switch from K&N to foam filter.
Need to build a heat sheild around the turbo. Seat cover is starting to melt on the right side. Heat is being transfered from turbo to the seat frame and melting the seat cover. That just happened this weekend at a demo event.
Running premium pump gas.

 

[mfridgen715]

fabro, are you saying that a blower will lose more hp compared to a turbo at elevation?

 

[gargamel]

If I understand it right, and please correct me if I am wrong here!

A supercharger will steal horsepower by imposing an extra load on the crankshaft, which is used (via gears, pulleys or both) to drive the compressor.



A turbocharger will steal horsepower by creating back pressure on the exhaust system, which drives the compressor with it's gases.

:exc:

Is that right?

Thanks

you are correct
Now which one is better?? You'll hear different answers from different people you talk to. IMO turbo's are better, but this is an age long debate

 

[teerex]

You can install turbo without touching the cylinder head gaskets, and lower the turbopressure to 6 psi . Some guys in Sweden have done this. The turbo lag disappeares, it gives about 110-115 hk, but this is not confirmed yet.

 

[rfabro]

fabro, are you saying that a blower will lose more hp compared to a turbo at elevation?

Yes. The new MCX kits for EFI automatically increase boost pressure as altitude increases and atmospheric pressure
decreases-- keeping the power output constant no matter your altitude. That's especially great for clutching and
when you consider there's a 3% power loss for every 1000 foot elevation gain- its even greater. Blowers are spun
by a belt transferred from the crankshaft-- to increase boost you must change to a smaller driven/larger drive
pulley to spin the compressor faster by way of taller gearing. I was set on a turbo, then a blower, now the turbo
again-- I live at only 5000ft but ride between 6&9000ft by my house. I will also be riding Colorado a bit in a little
while--with rides starting at 10,500ft+. I don't want to spend 5G's and only have 98 HP at 10,000ft! Also, think
about smoking all the naysayers! It would take a very heavily modified NA(naturally aspirated) machine to make
200HP at sea level, which would be reduced to 140HP(=phazer turb.) at 10,000ft. In other words a turbo phazer
will smoke just about every NA sled you will ever see! Reliability has been my major concern. What good is a powerful
mountain machine if it just breaks further out in the backcountry than you would otherwise be able to go? Good news
is, Yami 4strokes have an awesome record of turbo'd reliability-- if you don't boost too much. Like blue says, you
can even do a hybrid-- higher compression/lower boost for increased bottom end power and reliability. For the
record, my dealer, who owns a turbo mtn phazer, says the abrupt low end power from a blower is too much for
lower speed boondockin' and the turbo is mellow on the bottom. Also, I would probably buy the blower if I were
almost always at low elevation-- it would have the grunt of a V8! And it would have none of the heat problems
associated with turbos. Then you would just change pulleys on the blower set up if you were going to a high elevation.
One of the beauties of the MCX brain box is you can change tuning/boost at your truck with a laptop computer. Cool.
I will probably build my engine this summer with good crank, rods, pistons to make for years of reliability--
Also with a strong build you can boost up to something like 18psi and run 200HP with race gas. Whew! I will probably
not do that often. My big question is..... will the knock system still work? If it does, you're pretty much guaranteed
good reliability because the system will let you know if you're overboosting by way of detonation detection.
Then you just take it easy back to the truck and lower the boost a little on your laptop!

 

[mfridgen715]

thanks for the info, ok I am aware of the 3% and 140 turbo power being close to the 190-200 hp nat. range but I must of had a brain fart or something because I thought if you ran 10lbs boost on either the blower or the turbo they would be close at elevation considering that it was forced air induction. So the blower that is set up to run 8-10lbs at 1000' will not push that at 10,000 with out changing pullies? For the riding I do I don't need hybrid type fuel consumption or highmarking top end, I would rather have it pull hard and be snappy on low end. And yes most of riding I do is around 10,000' the stock 80hp is actually pretty good at 1000'. any info would be great just trying to make a decision and I am familiar with the mcx and how well it works but the people that I ride with that have them want peak hp and I thought I would try something different. thanks

 

[rfabro]

Yeah, I was torn between the two for a while- the altitude thing sealed the deal for me. Also, consistent power means consistent clutching.